In an effort to increase the utility of wireless communications, advances have been made to improve the probability of transmission and receipt of error free or error correctable information. It is known that data blocks transmitted over a communications link may be encoded with one of an available plurality of error correcting encoders. The data block is encoded by the transmitting device according to a known algorithm, for example a Reed-Solomon encoder. The encoded data block is received by a receiving device which then decodes the data according to an appropriate error correcting decoder. In this case, both the transmitting device and the receiving device have a priori knowledge of the error correction coding that is in use. Advantageously, if one or more bits in the transmitted data block is corrupt, the decoder used at the receiving device may detect and correct the corrupted bits, thereby allowing use of the transmitted data block. Error correction encoders/decoders are used to increase the throughput of the communications channel by obviating the need to discard and retransmit corrupted data blocks. Disadvantageously, in order to transmit an encoded data block, a portion of the data block is used as overhead in order to transmit the information for use in decoding the subject data block. Accordingly, the portion of the data block used to transmit error correcting encoding information cannot be used to transmit bits of information, thus reducing the throughput of the communications link. The reduction in the amount of data transmitted on a per data block basis due to the error correcting overhead is, however, worthwhile in view of the increase in average throughput over time due to the ability to use data blocks that would otherwise be discarded and retransmitted.
Wireless communication is used in many areas including mobile telephone, wireless LAN, and mobile voice and data networks. Wireless communications are also used in applications where both the transmitter and the receiver are physically stationary such as digital TV. One known type of communications protocol provides access to the transmission channel without use of a reservation protocol. An example of this type of communications protocol known in the wireless communications industry is the CDPD Communication System protocol for mobile devices communicating with a base station and is defined by the CDPD System specification Release 1.1 , January 1995, the contents of which are specifically incorporated by reference herein. As defined in Part 402 of the CDPD System Specification "Medium Access Control", Section 4.6, pages 402-21 through 402-24, reverse channel message blocks, which are defined as a series of data blocks transmitted from a mobile to a base station, are Reed-Solomon (63,47) encoded to improve the probability of successful transmission. Each forward and reverse channel message block is encoded based on a (63,47) Reed-Solomon code generated over a 64 bit Galois Field GF(64). The code word is based on 6-bit symbols. The information field consists of 47 6-bit symbols, comprising 282 bits, and the generated parity field consists of 16 6-bit symbols, comprising 96 bits, for a total encoded block comprising 378 bits. While the error correcting encoded data blocks provide for a more robust data transmission, the encoding scheme applied to all of the data blocks results in some sacrifice in channel throughput as compared to the theoretical maximum throughput value. In other cases, the (63,47) Reed-Solomon encoding is insufficient for successful transmission and results in a discarded transmission and retransmission. Retransmission of message blocks also adversely affects channel throughput.
Since maximizing channel throughput permits increased channel traffic without an increase in communication system infrastructure, it is desirable and cost effective to maximize channel throughput.
Another known communications link that provides access to the channel through a channel arbitration process uses a (63,45) Reed-Solomon error correction encoder for transmitted data blocks. Where CDPD controls access to the reverse channel using a slotted non-persistent Digital Sense Multiple Access with Collision Detection (DSMA/CD) method, other communications links include a direct channel arbitration method whereby the mobile requests access to the reverse channel and does not initiate a transmission of a data block on the reverse channel until the request for access to the channel is granted by the base station. Both types of communications links benefit from error correction, the optimum type and level of error correction being a function of the specific wireless network. Both types of communications links optimize average channel throughput by trading off instantaneous channel throughput in exchange for a more robust transmission by dedicating some of the data block in each datablock transmission to error correction overhead. Both types of communications links would benefit from maximizing information throughput.
There is a need, therefore, for a method to maximize the efficiency of the available bandwidth and throughput.